Well if it helps at all, when I was installing my gauges and msd box I found there was a big blue wire coming from the actually key part of the ignition. This was the power wire that only went to 12v when the key was turned on.
If you can´t find a diagram, pull apart the column and use a multimeter and simulate what you need with the ignition, find the wire that´s reading like 12.43v or whatever it was for me.
If you can´t find a diagram, pull apart the column and use a multimeter and simulate what you need with the ignition, find the wire that´s reading like 12.43v or whatever it was for me.